Electric hammer



L. TARWATER ELECTRIC HAMMER Jan. 27, 1953 Filed Aug. 14, 1950 2 SI'IEETS SI-IEET 1 FIG. 2.

$5 4 A v mun a aw um IM INVENTOR LAWSON TARWATER W W 9W4 ATTORNEYS Jan. 27, 1953 L, T w R 2,626,598

- ELECTRIC HAMMER Filed Aug. 14, 1950 2 SHEETSSHEET 2 FIG. 3.

90 INVENTOR 87 LAWSON 'TARWATER ATTORNEYS Patented Jan. 27, 1953 UNITED STATES PATENT OFFICE ELECTRIC HAMMER Lawson Tarwater, Redlands, Calif. Application August 14, 1950, Serial No. 179,239

9 Claims.

This invention has to do with power-driven hammers or tampers adapted to be held manually.

An object of the invention is to provide a novel, motor-driven tamper or hammer for manual use.

Another object is to provide a motor-driven tamping machine of novel construction which imparts rapid hammer blows to a tamping tool or other tool mounted therein.

A further object is to provide a tamping machine having novel, rugged and efiicient means for transmitting rotary motion into reciprocatory, rectilinear motion.

Another object is to provide a device of the type indicated which may be readily fabricated and assembled and one which is comparatively easy to handle when operated.

These and other objects will be apparent from the drawings and the following description thereof. Referring to the drawings:

Fig. l is an elevational view of a machine embodying the invention;

Fig. 2 is a central sectional elevational View through the machine of Fig. 1;

Fig. 3 is a partial plan View of the machine on line 3-3 of Fig. 2; and

Figs. 4-9, inclusive, are sectional views in the planes designated respectively 4-4, 5-5, 6-6, 8-8 and 39 on Fi 2.

More particularly describing the invention, reference numeral H generally indicates the tamping machine which is adapted to mount a suitable tool, such as a tamping tool l2 shown in broken lines in Fig. 1. While the device was designed principally for use in operating tamping tools, it will be apparent that the machine may be used for operating various tools where it is desired to impart rapid hammer blows to the tool.

The machine includes a suitable handle l4, 9. motor housing l5, a main or gear housing l6, and a tool housing I1. A hammer or hammer bar 26, which is contained partly in the main 110115! ing and partly in the tool housing, is reciprocated by a motor 2| through the medium of suitable mechanism'in the main housing for transforming the rotary motion of the motor shaft into rectilinear motion.

Proceeding with a more detailed description, the handle [4 includes a central plate or web 23 having two parallel spaced mounting portions 24 by means of which the handle is secured to the motor housing by means of bolts 25. The handle includes a pair of spaced side bars 21 and .these are connected at each end by tubular handle members 28 and 29.

The motor housing I5 is formed to provide a motor chamber 3| into which projects a plurality of ribs 32 for supporting the motor. The motor may be a press-fit within the ribs. The motor housing is also formed to provide a recess 33 for the reception of a motor shaft bearing 33a at the upper end of the motor.

I contemplate using an electric motor, however, the construction is such that other types of motors, such as a rotary air motor, for example, might be used. The upper end of the motor housing is provided with a cup-like recess 34 to receive a switch 35, and this is connected to the motor by suitable wires 36 and to a source of electric current by wires in a cable 31. A plate 36 serves to enclose the recess and act as a mounting element for the switch. The switch toggle lever 40 projects upwardly through an opening 4| in the plate 23 of the handle. If an air motor were used, the housing could carry the necessary control valve and could be provided with air intake and exhaust parts.

The lower portion of the motor housing accommodates a fan 43 mounted on the motor shaft 44. The fan serves to cool the motor by circulating air through the spaces between the ribs 32 in the motor housing and for this purpose a pair of openings 46 are provided in the motor housing on each side of the device, the openings communicating with the spaces between the ribs The motor housing is secured to the main housing 16 with the two in abutting relation by bolts 48. The main housing includes an upper wall 50 provided with a central opening 5| for mounting a. shaft bearing 52. The lower end of the motor shaft is fitted with a gear 53 and this meshes with a gear wheel 54 fixedly mounted on or integral with a shaft 56. This shaft is supported at one end in a bearing 51 mounted in a bearing housing 58 having a cover plate 59. The other end of theshaft is mounted in a bearing 6| supported in a depending wall portion 62 of the main housing. A second gear wheel 64 on shaft 56 meshes with a gear 65 on a crankshaft 66, the latter being supported in a bearing 61 mounted in the wall 62 and in a bearing 68 mounted in a bearing plate 69 secured to the main housing by bolts 10. The plate 69 has a cover plate 12 which covers the end of the shaft 66. The crankshaft 66 includes an eccentric or crank portion 15 and on this is mounted a connecting rod (Fig. 9), generally indicated by '16.

The connecting rod includes a pair of members I! and 1.8 which are complementary and together form a circular opening I9. A roller bearing assembly 80 is positioned between the member I6 and the crank portion 15 of the shaft. The two members 11 and I8 are secured together by bolts 82 and 83. At their lower ends the members TI and I8 are formed to provide a pair of spaced apertured extensions 11' and I8 in which is pivotally mounted a universal block 85 consisting of a central body 86 having a pair of trunnions 81 at opposite sides. This member is provided with an axial bore 88 which is adapted to receive the cylindrical pin-like end 90' of a lever 9|.

The lever 9| is pivotally mounted by means of a shaft 92 fixed therein and pivoted in bearings 93 and 94 (Fig. 6) in inwardly extending bearing cups 96, 91, formed in the main housing. The main housing is provided with apertures 98, 98', 99, 99 which are covered by plates I00, I.

The lever 9| is bifurcated at I02 to receive the upper end I03 of the hammer 20. The end I03 is pivotally connected to the lever by a pin [04 which passes through a hole I05 in the hammer, the hole being sufficiently large to permit of the arcuate movement of the pin. The hammer 20 is supported radially by a bushing I06 in the main housing and by a second or lower bushing I01 within a bore I08 in the upper end of the tool housing IT. The bushing II]? has a packing gland or seal ring I09.

The hammer 20 is formed with cylindrical smooth surface sections H2 and I I3 which are fitted for sliding movement within the aforementioned bushings. Intermediate its ends and within a spring chamber H5 formed in the main housing the hammer is provided with fiange I II. A compression spring H8 is interposed between this and a shoulder H9 in the housing. Thus, the hammer is constantly yieldably urged downwardly.

The tool housing I! is bolted to the lower end portion I2I of the main housing by bolts I22. I preferably provide a resilient connection at this point by providing the lower end of the main housing with a plurality of counterbores I23 of larger cross-sectional area than the bolts I22 and springs I24 are positioned in these counterbores. The upper end portion I25 of the tool housing is cylindrical and fits in a counterbore I26 in the lower end of the main housing.

The tool housing is formed to provide a tool guide wall I21 intermediate its ends and this is provided with a suitable opening I28 for receiving the tool I2, the opening being shown as hexagonal. The lower end of the tool housing has an enlarged bore or space I29 for receiving a flange or the like on the tool and a counterbore I30 below this in which is fitted a split tool bushing I3I held in place by screws I32.

In the operation of the device, assuming that a suitable tool has been mounted in the tool housing by removing the tool bushing I3I and subsequently replacing it with the shank of the tool projecting into the tool housing, rotation of the motor shaft 44 serves to operate the lever 9I through the medium of the gears and crankshaft and connecting rod with the result that the hammer 20 is reciprocated to operate the tool. The hammer is aided in its downward movement by the action of the spring I I8.

Although the invention has been particularly shown and described, it is contemplated that various changes and modifications can be made without departing from the scope of the invention as defined in the following claims.

I claim:

1. In a motor-driven tamping machine, a housing, a motor in said housing, a hammer bar mounted in said housing for axial movement, a crankshaft driven by said motor, a lever pivotally mounted between its ends in said housing, and a connecting rod on said crankshaft and connected to one end of said lever, the other end of said lever being directly pivotally connected to said hammer bar.

2. In a motor-driven tamping machine, a housing, a motor in said housing, a hammer bar mounted in said housing for axial movement, a crankshaft driven by said motor, a lever pivotally mounted between its ends in said housing, a connecting rod on said crankshaft and connected to one end of said lever, the other end of said lever being directly pivotally connected to said hammer bar, and a spring in said housing yieldably urging said hammer bar outwardly of said housing.

3. In a motor-driven tamping machine, a housing, a motor in said housing, a hammer bar mounted in said housing for axial movement, a crankshaft driven by said motor, a lever pivotally mounted between its ends in said housing, a connecting rod on said crankshaft and connected to one end of said lever, the other end of said lever being directly pivotally connected to said hammer bar, a tool housing section mounted at the end of said housing for limited movement with respect thereto axially of said hammer bar, said tool housing section providing a guide for axial movement of said hammer bar and guide means for axial movement of a tool received therein, and resilient means urging said tool housing section away from said housing.

4. In a machine having a motor, a reciprocatory axially movable hammer bar, and means operatively connecting the motor and bar, housing means comprising a motor and main housing structure for enclosing said motor and said hammer bar, a bearing in said housing structure slidably supporting said bar, a tool housin mounted at the end of said housing structure for limited movement with respect thereto axially of said bar, said tool housing providing a guide for axial movement of said bar and guide means for axial movement of a tool received therein, and resilient means urging said tool housing away from said housing structure.

5. In a motor-driven tamping machine, a housing, a motor in said housing, a hammer bar mounted in said housing for axial movement, a crankshaft driven by said motor and supported in the housing, a connecting rod on the crank portion of said shaft, a pivotally mounted block at the outer end of said connecting rod, a lever pivotally mounted intermediate its ends in said housing, one end of said lever being mounted for axial slidable movement in said block, and means pivotally connecting the other end of said lever to said hammer bar.

6. In means for transforming rotary motion of a shaft into reciprocatory motion in a driven element, a crankshaft driven .by said shaft, a connecting rod on the crank portion of said crankshaft, a block pivotally mounted in the outer end of said connecting rod, a lever pivotally mounted intermediate its ends, one end of said lever being slidably received in said block, and a relatively sloppy Pivotal connection between the other end of said lever and the driven element to be reciprocated.

7. A connecting rod structure comprising, when assembled, a pair of complementary members defining a crank-pin-receiving opening and a pair of spaced parallel apertured extensions thereheyond, bolts securing said members together, and a block having trunnions thereon pivotaliy mounted in said apertured extensions, said block having a bore thei'ethrough for the reception of a lever to be actuated.

8. In a motor-driven tamping machine, a housing structure including a main housing with a motor housing at one end and a tool housing at the other, said tool housing being mounted for limited movement toward and away from said main housing, means yieldahiy urging said tool housing away from said main housing, a motor in said motor housing, a hammer bar in said main housing projecting into said tool housing, a bushing in said main housin for siidably receiving said hammer bar, a bushing in said tool housing siida-loly receiving said hammer bar, additional bushing means in said tool housing for slidably receiving a tool therein, and means in said main housing operatively connecting said motor and said hammer bar for reciprocating said hammer :bar axially.

9. In a motor-driven tamping machine, a housing structure including a main housing with a motor housing at one end and a tool housing at the other, said tool housing being mounted for limited movement toward and away from said main housing, means yieldabiy urging said tool housing away from said main housing, a motor in said motor housing, a hammer bar in said main housing projecting into said toolhousing, a bushing in said main housing for siidahly receiving said hammer bar, a bushing in said tool housing receiving said hammer bar, and means in said main. housing operatively connecting said motor and said hammer bar for reciprocating said ham-- mer bar axially, said last-"mentioned means comprising a crankshaft driven by said motor, a con.- necting rod on the crankshaft, and a lever pivotaily mounted between its ends in said main housing connecting said connecting rod and said hammer bar.

LAWSOi i TARWATER.

REFERENCES CETED The following references are of record in the file of this patent:

UNITED STATES PAIENTS Number Name Date 709,820 Jackson Sept. 23, 1902 751,522 Koch Feb. 9, 1904 1,642,560 Schellerer .a Sept. 13, 192? 1,778,547 Brown Oct. 14, 1930 1,959,516 Baker May 22, 193% 2,519,477 Kind Aug. 22, 1950 FOREIGN PATENTS number Country Date 329,650 Germany Nov. 27, 1920 

